This project is a biomedical engineering approach to obtain a quantitative understanding of fetal head molding during pregnancy and parturition. A review of the literature indicates that molding is only poorly understood qualitatively while quantitative information is nonexistent. As a first step towards understanding the process, we are investigating the mechanical tissue properties of fetal cranial bone and dura mater. Tests are being performed to quantify the elastic modulus in tension, Poisson's ratio, bending modulus, relaxation modulus, and the degree of nonlinearity in these quantities, if any. Testing will also allow comparison of mechanical properties between cranial bones, an assessment of the degree of transverse isotropy within any bone, and an assessment of the effects of gestational age particularly with regard to prematurity. A knowledge of the mechanical properties is the first step towards a long-term goal of developing a structural model of the fetal head. Such a model would allow quantitative predictions of the amount of head molding which would be reflected in fetal mortality and morbidity (viz., cerebral palsy or mental retardation).